#include <stdio.h>
#include <stdlib.h>

#define	LOCAL	static
#define	EXPORT	/* */

typedef	unsigned char	UB;
typedef	signed char	B;
typedef	unsigned short	UH;
typedef	signed short	H;
typedef	unsigned long	UW;
typedef	signed long	W;
typedef	unsigned int	UINT;
typedef	signed int	INT;


typedef	_Packed struct _pnpheader {
	UW	signature;			// +0x00
	UB	version;			// +0x04
	UB	length;				// +0x05
	UH	control_field;			// +0x06
	UB	checksum;			// +0x08
	UW	event_notification_flag;	// +0x09
	UH	realmode_code_offset;		// +0x0d
	UH	realmode_code_segment;		// +0x0f
	UH	protectedmode_code_offset;	// +0x11
	UW	protectedmode_code_segment;	// +0x13
	UW	oem_device_identifier;		// +0x17
	UH	realmode_data_segment;		// +0x1b
	UW	protectedmode_data_segment;	// +0x1d
} PnPHeader;

#define	PnPBIOSEntry(ptr)	\
	(void far *)(((UW)ptr->realmode_code_segment << 16) | \
			 (ptr->realmode_code_offset));

LOCAL	void far *find_pnpbios(void)
{
	UW	adr;
	UB	sum;
	UB	far *ptr;
	INT	i, len;

	for (adr = 0x000f0000; adr < 0x00100000; adr += 0x10) {
		ptr = (UB far *)((adr & 0x0000ffff) |
				 ((adr & 0x000f0000) << 12));

		/* check "$PnP" header */
		if (*(UW far *)ptr != 0x506e5024) continue;

		/* check length */
		len = *(ptr + 5);
		if (adr + len >= 0x00100000) continue;

		/* calc checksum */
		sum = 0;
		for (i = 0; i < len; i++) sum += *(ptr + i);
		if (sum) continue;

		return ptr;
	}

	return NULL;
}

LOCAL	void	dump_pnpheader(PnPHeader far *ptr)
{
	printf("[$PnP: 0x%08lx]\n", ptr);
	printf("Signature					0x%08lx\n",
	       ptr->signature);
	printf("Version						0x%02x\n",
	       ptr->version);
	printf("Length						0x%02x\n",
	       ptr->length);
	printf("Control Field					0x%04x\n",
	       ptr->control_field);
	printf("Checksum					0x%02x\n",
	       ptr->checksum);
	printf("Event notification flag address			0x%08lx\n",
	       ptr->event_notification_flag);
	printf("Real Mode 16-bit offset to entry point		0x%04x\n",
	       ptr->realmode_code_offset);
	printf("Read Mode 16-bit code segment address		0x%04x\n",
	       ptr->realmode_code_segment);
	printf("16-Bit Protected Mode offset to entry point	0x%04x\n",
	       ptr->protectedmode_code_offset);
	printf("16-Bit Protected Mode code segment base		0x%08lx\n",
	       ptr->protectedmode_code_segment);
	printf("OEM Device Identifier				0x%08lx\n",
	       ptr->oem_device_identifier);
	printf("Real Mode 16-bit data segment address		0x%04x\n",
	       ptr->realmode_data_segment);
	printf("16-Bit Protected Mode data segment base address	0x%08lx\n",
	       ptr->protectedmode_data_segment);

	return;
}

/* Function 0h - Get Number of System Device Nodes */
LOCAL	UH	pnp00h(PnPHeader far *ptr, UB *NumNodes, UH *NodeSize)
{
	H	(__cdecl far *entry)(H Function, UB far *NumNodes,
				     UH far *NodeSize, UH BiosSelector);
	UH	result;

	entry = PnPBIOSEntry(ptr);
	result = (*entry)(0x00, NumNodes, NodeSize,
			  ptr->realmode_data_segment);

	return result;
}

/* Function 40h - Get PnP ISA Configuration Structure */
LOCAL	UH	pnp40h(PnPHeader far *ptr, UB *Configuration)
{
	H	(__cdecl far *entry)(H Function, UB far *Configuration,
				     UH BiosSelector);
	UH	result;

	entry = PnPBIOSEntry(ptr);
	result = (*entry)(0x40, Configuration, ptr->realmode_data_segment);

	return result;
}

/* Function 41h - Get ESCD Info */
LOCAL	UH	pnp41h(PnPHeader far *ptr, UH *MinESCDWriteSize, UH *ESCDSize, UW *NVStorageBase)
{
	H	(__cdecl far *entry)(H Function, UH far *MinESCDWriteSize,
				     UH far *ESCDSize, UW far *NVStorageBase,
				     UH BiosSelector);
	UH	result;

	entry = PnPBIOSEntry(ptr);
	result = (*entry)(0x41, MinESCDWriteSize, ESCDSize, NVStorageBase,
			  ptr->realmode_data_segment);

	return result;
}

EXPORT	INT	main(int argc, char *argv[])
{
	PnPHeader	far *ptr;

	ptr = find_pnpbios();
	if (ptr == NULL) {
		printf("PnP Header not found\n");
		goto fin0;
	}

	dump_pnpheader(ptr);

{
	UB	z;
	UH	r, y;

	r = pnp00h(ptr, &z, &y);
	printf("%x %x %x\n",
	       r, z, y);
}

 fin0:
	return 0;
}